Patient comfort and positioning are important goals of all medical procedure chairs. Additionally, particular medical specialties have requirements beyond these basic considerations. For example, dermatologists, plastic surgeons, oral maxillofacial surgeons and specialists practicing otolaryngology require maximum access to the head and neck area of patients. Other medical specialists, such as gynecologists, proctologists and podiatrists have different desired features in procedure chairs. Thus, for procedures involving the head and neck area of patients, it is preferable that the position of the headrest be adjustable and that the neck area be narrow. The specific configuration of the headrest itself should be variable to accommodate different types of procedures involving the head. It is desirable, therefore, that the headrest, on the one hand, be easily positionable and readily locked in a desired position, and on the other hand, that headrests of different sizes and shapes can be quickly and easily substituted to enhance the performance of different types of procedures.